Investigations of personal human ergonomic design in automotive interaction.

Kipke, Jasna Jurum ; Kovacevic, Drazen ; Sumpor, Davor 等

1. INTRODUCTION

Physiological anthropology is a branch of science which studies the functions and processes of living organisms and their parts and organs. From this aspect, the main task of the physiological anthropology is to study the differences among people, and how and in which way the single body parts work together with the aim of achieving some of its working functions (Muftic et al., 2001).

In human organism no property is constant for a longer period of time. Human body consists of heterogeneous materials and its properties are different for different parts. The gender is also a very significant factor in designing a computer 3D model (Mijovic et al., 2001).

The human body is very complex and it is practically impossible to describe all the movements that a body can produce. The complexity of movements results from the fact of a large number of degrees of freedom of the movements and therefore many assumptions and simplifications are introduced into the analyses of the human movements in space.

The problem of adjusting the activities to humans is studied through the analysis of the static and dynamic workloads, researching the groups of the most favourable postures and extremities during work.

In order to solve the problems related to the body mobility a correlation between the biomechanical and anthropometric research is necessary. All body movements consist of different basic movements of its single parts and in single joints. Thus the success of complex movement depends on the type and scope of these individual movements. The body as a living organism is a much more complex system than any today known technical construction, with a huge number of interacting elements. Observing the body parts of different masses and dimensions as parts of the kinematic chain, and analyzing different body postures in resting and in motion from the aspect of biomechanics, it is possible to find the optimal types of movements as part of a technological process, thus preventing the unnecessary fatigue or illness.

2. BIOLOGICAL ANTHROPOMETRIC ANALYSIS

Anthropometric measures that are of relevant interest for ergonomic considerations will depend on the type of working activity and on the requirements of the working process, most in the so-called condition of active work. Therefore, the considerations include all those dimensions of the human body that form the sum of the relations subject to performing of certain work task, as well as the environment in which the human stays and works. Thus, every ergonomic anthropometric research requires the application of some specific measures as well as definition of some new factors that are necessary to determine the morphological specifics of human body, in relation to a certain purpose (Maver et al., 1976).

The list of ergonomic anthropometry is continuously supplemented by measures that do not only indicate the possibility of adequate action of the tested system, but can also perform a certain task given to the subject, in the most adequate and optimal working posture. It is necessary to determine also the diverse possibilities of taking the most favourable work position, and movement in the given space having at the same time in mind also the considerations of the space dimensions, sizes and shape of the work environment. Such research and the resulting solutions have to completely satisfy the basic biomechanical, biomedical and ergonomic requirements (Muftic & Milcic 2001).

3. BIOMECHANICAL ANALYSIS

Acquiring precise knowledge about the dimensions and parameters of the human body and the creation of the biomechanical model that will best simulate the actual conditions is the basic task during computer biomechanical movement analysis. The basic values necessary to describe the movement are anthropologic measures, i.e. the lengths of the human body segments, segmental mass and their distribution according to the selected coordinate system.

Since the human skeleton contains: 95 joints with one degree of freedom of movement, 80 joints with two degrees of freedom of movement, and 75 joints with three degrees of freedom of movement, which results in a total of 250 degrees of freedom of movement, the entire complexity of the kinematic and dynamic study of the human skeleton is understandable. This is significant because the mobility of the computer-designed 3D model depends on the degrees of freedom of movement of its basic components (Muftic et al., 2001).

Precise analysis of the human body movement within a three-dimensional space is a very complex and demanding task. In numerous examples of research, the factors of movement are usually simplified to such an extent that there are obvious deviations of the computation results from the measured ones. Therefore, there is also the need to find more adequate digitized methods that, apart from certain methodological benefits would insure also more reliable results (Baksa et al., 2007).

4. RESEARCH RESULTS

For the research of personal body interaction and ergonomic harmony while performing the work of opening the back door, putting the travelling bag into the trunk and closing the car doors, a male subject was selected, 190cm tall, with a mass of 83kg, and the selected test car was compact, B segment, Hyundai, Getz model. By using the new and advanced contactless 3D body scanner "BodySABA 0.7.", the digitally generated three-dimensional model of the subject was used to read all the relevant anthropometric measures, and Table 1 presents characteristic anthropo-measures of the standing work posture.

In order to make a computation of individual biomechanical characteristics of work and ergonomic analysis of the work performance of the tested measuring subject "SABALab" system was used, of three-dimensional measurements and analysis of the work of humans, the so-called MoCap system, "FatoSABA 2.1.", as can be seen from the characteristic kinematograms in Figure 1.

[FIGURE 1 OMITTED]

Table 2 gives a presentation of measurement values of angles a between the forearm and upper arm and angles p between the hand and the forearm of the working extremity. Since the subject handled a travelling bag during the analysis, and it was a person usually using the right hand, the working procedure of opening the door with left hand (lh) was understandable and the closing with the right hand (rh).

The results that range within the limits [96.42.sup.0] to [142.15.sup.0] for angle [alpha] and [121.11.sup.0] to [181.49.sup.0] for angle [beta], show the ergonomic compatibility of the tested subject and the automobile.

5. CONCLUSION

By knowing the anthropometric measures and with the application of computer equipment, computer 3D graphic software and instruments, e.g. the system of "BodySABA" and "FatoSABA" systems, it is possible to perform very efficiently and very fast the ergonomic modelling and the analysis of dimensions and forms of elements of the working environment system in order to make judgement on the spatial performance of the ergonomic design of the working automotive environment with regard to the diversity of the motorist and their understanding of the comfortable working posture.

The carried out bio-mechanical analysis, based on anthropometric research and the use of computer biomechanical models, allows digitization of the actual activity and results in the researched indicators that contribute to the knowledge on more acceptable and better design of the working ambient system of automobiles in interaction with the customers.

The guidelines of future research are directed to the possibility, based on the software-processed video-recording, of carrying out adequate ergonomic analysis of any form of physical effort in humans, of classified values to adequate statistical distribution of the defined domicile as well as world population.

6. REFERENCES

Baksa, S.; Muftic, O. & Sumpor, D. (2007). Computer Aided Ergonomics Analysis of Exhibition-transport element, Proceedings of 3rd International Ergonomics Conference, Ergonomics 2007, Mijovic, B. (Ed.), pp. 249-257, ISBN 987-953-98741-4-6, Stubicke Toplice, Jun, 2007, Zagreb.

Maver, H.; Rudan, P. & Tarbuk, D. (1976). Practical work in anthropology, Ergo. metode, Ant. Bib., Zagreb

Mijovic, B.; Ujevic, D. & Baksa, S. (2001). Visualization of Anthropometric Measures of Workers in Computer 3D Modeling of Work Place. Collegium Antropologicum, 25., 56., (2001), 639-650.

Muftic, O.; Veljovic, F.; Jurcevic-Lulic T. & Milcic D. (2001). Fundamentals of ergonomy, Masinski fakultet, Sarajevo.

Muftic, O. & Milcic, D. (2001). Ergonomy and safety, Visoka skola za sigurnost na radu, Zagreb, Iproz, Zagreb

Tab. 1. Characteristics of anthropometric measures of the
subject for standing work posture.

 Values of
 anthropo-
 Symbol and name of measures
 anthropometric measures (cm)

A Standing height 190,0
B Height of eyes (standing) 179,0
C Height of shoulders (standing) 156,5
D Height of elbow above floor 118,0
E Height of knee of a standing person 54,8
F Arms span 201,0
H Length of forearm with hand 51,8
I Width of shoulders 49,8
K Bust measurement (chest) 24,3
L Thigh width 34,5
V Foot length 29,5
X Foot width 10,6
Y Hand length 21,5

Tab. 2. Measuring values of angles of the working extremity
of the subject.

 Measuring value of angle ([sup.0])
 Sequential
kinematogram [alpha] [beta]

 a) 142,15 (lh) 178,94 (lh)
 b) 96,42 (lh) 124,88 (lh)
 c) 110,34 (lh) 155,31 (lh)
 d) 134,39 (lh) 168,73 (lh)
 e) 141,29 (lh) 172,43 (lh)
 f) 132,42 (rh) 140,84 (rh)
 g) 118,22 (rh) 121,11 (rh)
 h) 110,58 (rh) 181,49 (rh)
 140,65 (rh) 149,94 (rh)